In the prior art, applicant is aware of applicant's own United States Patent Application, publication number US2008/0295417, published Dec. 4, 2008, for an Inflatable Beam Truss and Structure. In that patent application applicant describes a segmented inflatable beam truss which includes at least first, second, and third separate inflatable beams mounted to one another and having, respectively, first, second and third lengths and a substantially constant diameter amongst all of the three beams. Each beam includes an outer flexible substantially non-resilient sleeve along the entire length of the beam and an inner inflatable bladder extending substantially along and in the entire length of the sleeve. The applicant further teaches therein that, contrary to conventional wisdom which would require that pneumatic beams be increased in diameter as their length increases in order to support larger enclosures, that the use of a relatively narrow high aspect ratio pneumatic beam, where a plurality of such beams are mounted to one another, may be used to span relatively great distances if the beams are combined in side-by-side parallel array to form a single segmented beam truss. In jurisdictions allowing in corporation by reference, I hereby incorporate herein the aforesaid United States Patent Application Publication number US2008/0295417.
The drawback of that earlier design was that for use in high aspect ratio pneumatic beams I determined that the use of high pressurization was advantageous but caused the earlier design to fail. I have now found that using the airbeam of the present invention, for example as a twinned tube airbeam, or as an airbeam having a greater plurality of highly pressurized pneumatic tubes, that a greater stability may be achieved than I achieved in the past, where the airbeam resists twisting of the beam as it spans a long distance, for example forty-eight feet, and resists buckling at the vertex of the curvature when the airbeam is bent to provide a curved supporting member. Consequently, the earlier design had to be redesigned to allow for high pressurization for example pressurization exceeding 45-50 psi. As described below, the design of the present invention has been successfully tested at pressurization to 110 psi.
At high pressurization, I have found that the use of the earlier design, namely, the use of a single sleeve containing a resilient inflatable inner tube, failed along the stitching lines. Without the use of inverted sleeves and folded over, laterally spaced apart internal flat seams according to one aspect of the present invention, the expansion of the fabric at the seams allowed the resilient material, for example rubber, of the inflatable inner tube to push and expand into the spaces by bulging of the rubber between the stitching of the separating seams. I postulate that the bearing of the bulging rubber against the strands of the stitching increased the likelihood of failure along the seam.
The use of the highly pressurized airbeams according to the present invention was found to allow significant loading on the structure being supported by a plurality of such airbeams, when bent, so as to allowing forming for example of a dome or a quonset shape, when the ends of the bent airbeams are anchored to, for example, a floor panel or structure, and wherein the bending and the eventual domed or curved shape of the airbeam is governed by the curved shape of elongate fabric lumens formed in the flexible membrane of the domed structure.
Consequently, it is an object of the present invention, without intending to be limiting, to provide an airbeam capable of withstanding high pressurization and employing a plurality, for example, a pair of reinforced pneumatically inflatable beams mounted to one another so that the collective air beam is stabilized and resists twisting or buckling.
Other examples of pneumatically inflatable structures that I have designed may be found in for example, United States Patent Application Publication No. US2010/0175330 published Jul. 15, 2010, for an Inflatable Multi-Tube Structure, United States Patent Application Publication No. US2008/0210282, published Sep. 4, 2008, for an Inflatable Tent for Mounting into the Bed of a Pickup Truck, United States Patent Application Publication No. US2008/0313970, published Dec. 25, 2008, for an Inflatable Structure for Covering Sport Utility Vehicles, Boats and the Like, United States Patent Application Publication No. US2005/0197212, published Sep. 8, 2005, for an Inflatable Sport Ball Arresting Structure, United States Patent Application Publication No. US2007/0137113, published Jun. 21, 2007, for an Air Distribution System for Inflating Pneumatic Structures, United States Patent Application Publication No. US2008/0190472, published Aug. 14, 2008, for an Inflatable Structure for Covering Sport Utility Vehicles, Boats and the Like, United States Patent Application Publication No. US2009/0249701, published Oct. 8, 2009, for an Inflatable Quonset and Domed Structure and the Like, and U.S. Pat. No. 6,263,617, issued Jul. 24, 2001, for an Inflatable Self-Erecting Tent.
There is other prior art in the area of inflatable structures, for example, U.S. Pat. No. 6,260,306 which issued Jul. 17, 2001, to Swetish et al. for an Inflatable Shelter. Swetish et al. disclose an inflatable shelter having elongate inflatable tubes supported by the flexible membrane of the shelter so that a pair of the tubes form four legs supporting the membrane and wherein sleeves in the membrane define corresponding lumens for receiving the inflatable tubes. The lumens of the pair of sleeves are separated by at least one divider panel which extends substantially parallel to the pair of tubes.